Did anyone have a look at the Blackmoor Adventure in Dungeon #115 called Raiders of the Black Ice? I think I have that issue of Dungeon somewhere, but I don't know where I put it. Was it any good?
Maps for the module can be downloaded here:

The map shows gives a detailed look at the Greyhawk version of Blackmoor. I'm thinking about stealing some of the locations from the Greyhawk version and putting them into the Mystara one. Thoughts? I should probably leave out the "Black Ice" itself since that seems to be kinda iconic for Greyhawk, though I wouldn't be above having a Glacier in the Skandahar lands...

It will take quite some work to adapt this Greyhawk-Blackmoor adventure to DA or ZG Blackmoor, but it is not impossible and, I think, it will prove quite satisfactory, at the end.
For example you could replance the Raiders of Black Ice with Skandaharians and the Lands of Black Ice to a Skandaharian land (but then you need to convert a fair part of the trip from a land trip to a sea trip, unless you assume that all the sea north of Blackmoor is completely frozen). The master kidnapper could be the Egg too.
You will also need to identify a suitable village (although Tonnsborg sounds so close to a settlement once part of the Great Svenny's dominions, it can't be associated with that, as it is a hamlet of twenty houses, while the Great Svenny's one had a tower and dungeons, etc.) and find a suitable reason why the ruler of Blackmoor doesn't want to send his army, forcing a group of four adventurers to do all the job by themselves instead.